English

Abstract

Introduction Acute kidney injury develops in up to 30% of patients, who undergo cardiac surgery, with up to 3% of patients requiring dialysis. The requirement for dialysis after cardiac surgery is associated with an increased risk of infection, prolonged stay in critical care units and long-term need for dialysis. The development of acute kidney injury is independently associated with substantial shortand long-term morbidity and mortality. Its pathogenesis involves multiple pathways. Haemodynamic, inflammatory, metabolic and nephrotoxic factors are involved and overlap each other, which lead to kidney injury. High-risk patients can be targeted for renal protective strategies. Nonetheless, there is little compelling evidence from randomised trials supporting specific interventions to protect or prevent acute kidney injury in cardiac surgery patients. The aim of this critical review was to discuss the peri-operative renal protective strategies in cardiac surgery. Conclusion Several strategies have shown some promise, including less invasive procedures in those with greatest risk, natriuretic peptide, fenoldopam, preoperative hydration, pre-operative optimisation of anaemia and postoperative early use of renal replacement therapy. Large-scale trials are required to confirm their efficacy. Introduction Pharmacological interventions have been inconsistent with their efficacy, and currently there are no known drugs that have conclusively conferred renal protection. This failure might be related to a number of factors, which are as follows: • The pathophysiology of acute kidney injury (AKI) following cardiac surgery is complex, and simple approaches to target single pathways are unlikely to succeed. • Late pharmacological intervention (measured by a rise in serum creatinine [sCr]) is likely to meet with failure. By the time sCr is elevated, the person may already have lost 50% of kidney function. • Patient populations that have been studied are often at low risk for renal dysfunction post-cardiopulmonary bypass (CPB); thus, potentially masking small beneficial effects of therapies. • Most clinical trials enrolled a small number of subjects and are therefore, inadequately powered to detect small benefits. Renal protective strategies are summarised in Table 1. This critical review describes the various renal protective strategies being used in cardiac surgery.